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stevecarpy

My RD250LC Project

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Yep good point RZR a little thing like matching the ports(blue printing) is often over looked and so simple to do,, same with the cylinder base gasket they all need to be trimed/matched for good flow. A proper trimed base gasket can yeild 1-2 hp alone with matching ports ,,knife edge the intake bridge and 2-3 more hp with the bottom matched.Them motors wernt hard to get a extra 5 hp out of just by blue printing the motor from the intake to exhaust.

This should be a very nice finnished project with all the new NOS parts :popcorn:

Just in case you don't know how or what blue printing is ,,it's simple just get blue tool makers ink and assemble everything where the ink dosent make a imprent then it needs to go/ be matched small amount of work = big gains

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Trim the base gasket to match the port openings.

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Then transfer the base gasket to the case. Trace the gasket on the top of the case. Some layout dye will help.

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Take a dremel with a carbide cutter and cut to the scribed pattern.

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It's not to hard to do. Very worthwhile.

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I dunno. Not sure I'd trust myself doing that.

I can't do it now anyway engines back together.

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I've literally just sent barrel to be ported. WIthout the crankcases being done it's pointless I take it? It's for my TZR 4DL project.

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No problem, they can be done separately. There are hp gains to be made in both places.

Any 2 stroke can benefit from it. There is always a mis-match when parts are cast. When the case is not 'matched' to the cylinder, the flow becomes turbulent where the base gasket sit. There is not a smooth transition at this point because the base gasket protrudes into the transfer port. By making sure everything is matched, you get smoother flow. Smoother flow means a better charge. Better charge means more hp.

If you can do the work yourself, it's free hp

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I've literally just sent barrel to be ported. WIthout the crankcases being done it's pointless I take it? It's for my TZR 4DL project.

Nice bike BTW. I'd like to see some pics of it. Always love seeing those smokers. Especially Yamaha ones. :)

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Haha, Unfortunately It's not a 4DL bike. It's just the motor that i'm dropping into a Yamaha DT125RE that I supermoto'd using Aprilia RS125 Wheels and WR450F forks.

I've got a tasty little mod being hand made as we speak. Should look to get it on in a couple of weeks. Very excited.

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did the port matching on the Gilera, 1 hp extra on that is like 15% of total HP :babyha:

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That is a massive gain drewps,,, :thumb: .shall it be fit for foamys DT50 in a drag at squires.. :ssst:

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That is a massive gain drewps,,, :thumb: .shall it be fit for foamys DT50 in a drag at squires.. :ssst:

still got to get it registered then fit the spanny and then dial in the carb settings.

not sure if I'll go on it, I'll see nearer the time :)

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He Jeff the bridge in the cylinder port ,,,knife edge it up about 3/16th of a inch and finnish up your porting with a 80 grit finninsh stone you will have to keep it oiled and work at a slower speed RPM wise so it dosent plug up with mettal but it more free hp. And its easier to see any low/high spots you may have created in the roughing stage basicaly your at a stage 2 port now stage 3 is all the stuff I said above

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Hey Flip, I was thinking about the knife edge, but there seems to be a big debate on the RZ forum over it. A lot of the more expert tuners are saying that the knife edge was the NOT the way to go. I had always thought it was better. They are saying that a rounded edge is better. I just left it rounded as I wasn't ready to commit to the knife edge - I can always knife edge it later. Harder to put material back on than it is to take off.

I also need a 90 degree grinder. I need to get in the areas where the ports enter the cylinders. Just need to clean more of the casting flash better.

Good tips though.

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ER Um we just jacked his thread ask me on your build I want to see how this turns out

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Cheers Rez. I'm waiting till I can get my hands on a car so I can take it off the road properly.

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Hi all, sorry it's been a while. The build has progressed slowly and had to stump up some cash :-(

Gearbox components went in

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To be fair that was easy but I had bag and tagged everything. Next thing was to drop the crank in

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I Yamabonded the crankcase half and put the 2 together and torqued up

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Time to start fitting the outer components

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Clutch basket on

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Electrickery on

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Then disaster struck

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Decided to bite the bullet and bought one of these - hmmmm billet porn :-)

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Hardest part was drilling off the old gear ring without wrecking everything but that was successful

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Fitted back on engine

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Sorry about the pic heavy post, I'll put the others on shortly

Cheers

Steve

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